Entering the test menu on Data East and Sega games
On games up to Frankenstein, latch the green coin door button in its lowered position and then use the black button: one press opens the tests and each further press moves on to the next test. Baywatch and Batman Forever use a menu ("portals"): press the black button, move to the diagnostics icon with the flipper buttons, and choose it with the start button.
Systems
Related tips
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)